1. Field of the Invention
The present invention is broadly concerned with an improved tool designed for workpiece manipulation and which includes as a part thereof structure for imparting sharp, impulse-type loads to the tool so as to facilitate operation thereof. More particularly, it is concerned with such a tool which, in preferred forms, is designed for installation or removal of electrical appliances such as connector elbows, and which includes an elongated rod having a slidable hammer thereon with appropriate anvil surfaces coupled to the rod and engageable by the hammer for developing impulse-type forces.
2. Description of the Prior Art
Pad-mounted transformers and other URD electrical equipment are conventionally provided with terminator appliances connecting the equipment with underground transmission and distribution lines. These terminators normally include a central conductor and are configured for reception within complemental bushings or the like provided on the transformer or other equipment. For example, many pad-mounted transformers in use today include annular cup-like bushings on the forward tank wall thereof which are adapted to receive L-shaped terminator elbows in order to connect the transformer into the URD system. During installation, these elbows are normally coated with silicone grease or other type of lubricant and are installed over the complemental transformer bushings. Over time however, the silicone grease inevitably tends to harden with the result that a firm bond is established between the elbow and bushing. This problem is aggravated since in many instances terminator elbows will be removed only at very infrequent intervals (e.g., five years or more), and thus it is a quite common occurrence to find that the elbows are rigidly stuck in place and impossible to remove by hand even if this were an accepted practice.
It has been suggested in the past to provide elongated, insulative elbow pulling poles which are intended primarily to permit removal of terminator elbows without the necessity of grasping the same by hand or with conductive metallic tools. In general, these pulling poles comprise only an elongated hot line tool having a detachable elbow-gripping fixture secured to the forward end thereof. In use, the hot line tool is manipulated to close the elbow grippers around the stuck elbow, whereupon the lineman attempts to jerk the elbow free. This practice is of course undesirable since the lineman must in many instances exert considerable force on the elbow in order to free the same.
Furthermore, prior elbow pulling tools of this type have proven to be somewhat deficient in that flashover to ground can occur between the energized contact of the elbow and adjacent grounded surfaces during elbow removal. This problem can result when the lineman does not pull the terminator cleanly from the corresponding bushing so that the elbow contact and a grounded surface are in relatively close proximity for a period of time sufficient to permit sustained arcing. This arc may flash to the nearest grounded point such as the transformer tank wall if the transformer is of the dead-front type.
A greatly improved elbow puller is disclosed in U.S. Pat. No. 3,962,770. In this device, an elongated pushrod is pivotally linked to an insulative elbow-gripping pole; the pivotal linkage permits relative axial movement between the pushrod and pole so that appropriate manipulation of the tool simultaneously creates a pushing force through the pushrod and a corresponding, multiplied, oppositely directed pulling force on the elbow-gripping pole in order to quickly and smoothly detach the elbow. Elbow pullers of the type described in this patent have proven to be very serviceable, and a decided improvement in the art. Nevertheless, these pushrod-type pullers do not provide any real degree of assistance during elbow installation, which should likewise be accomplished on a relatively quick, smooth basis.
Other prior art patents describing various types of manipulative tools include: U.S. Pat. Nos. 634,276, 981,857, 1,938,419, 2,646,304, 2,934,984, 3,030,837, 3,175,705, 3,444,578, 3,534,993, and 4,034,594.